Display brightness cannot be adjusted 18.04

An alternative method is to install a PPA and brightness APP which also adjusts gamma - AWESOME!, and ... for any individual screen TOO!

Here are the 3 simple steps:

$ sudo add-apt-repository ppa:apandada1/brightness-controller
$ sudo apt update
$ sudo apt install brightness-controller

Then find it ...

Brightness Controller

in your App's/Accessories

Always Trying to help, Mark

I had the same issue on a Dell XPS 13. Found this link that solved the problem for me : https://bugs.archlinux.org/task/58296#comment168869

What I did:

• changed the content of /etc/default/grub by adding video.only_lcd=0 to GRUB_CMDLINE_LINUX_DEFAULT
• updated grub with sudo update-grub

After restarting the laptop, I was able to control the brightness.

I had the same problem some years ago and was having the same problem again after installing ubuntu 18.04. it was a kernel problem then, and i think it may be a kernel problem now.

After updating the kernel the problem was fixed for me.

To update kernel see: Updating kernel question

To download last stable kernel (which worked for me): http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.16.6/

In my case i downloaded:

  linux-headers-4.16.6-041606_4.16.6-041606.201804300418_all.deb

  linux-headers-4.16.6-041606-generic_4.16.6-041606.201804300418_amd64.deb

  linux-image-unsigned-4.16.6-041606-generic_4.16.6-041606.201804300418_amd64.deb

  linux-modules-4.16.6-041606-generic_4.16.6-041606.201804300418_amd64.deb

I've been struggling for the past week on trying to get Ubuntu working on my Dell XPS 15 9570 and I've had it working for a while with nomodeset but it's been killing my eyes having the display stuck on full brightness.

I finally fixed it today! I updated my kernel to 4.17 (http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.17/) which was last updated two days ago and then restarted, and then finally restarted again without the nomodeset option (and didn't have to replace it with anything) and the display works now!!!

Hope this helps :)

I have an XPS 15, and the following solved it for me:

1. Updating to the latest kernel (4.17.5 is the one I used, following instructions from this answer)
2. Reboot
3. Remove any video options (nomodeset, video.only_lcd=0, etc.) from the GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub file.
4. Run update-grub to update
5. Reboot

This made it possible to adjust from the keyboard and made "night mode" actually change screen colors.